Hi, A number of conditions may lead to postmenopausal bleeding such as Endometrial atrophy,polyps, Endometrial hyperplasia (thickening of the uterine lining), malignancy, vaginal atrophy. Endometrial atrophy (thinning of the uterine lining): The endometrium is the tissue that lines uterus. It responds to hormones like estrogen and progesterone. Low hormone levels after menopause can cause it to get too thin. This may trigger bleeding. Bleeding is often a side effect of certain drugs, like hormone therapy, tamoxifen, and blood thinners. Physical examination, Transvaginal ultrasound and endometrial biopsy which involves cutting and examining a small section of uterine lining for any abnormal cells should be carried out to determine the cause. Hope that was helpful. Let me know if I can assist you further. Get well soon. Regards, Dr. Saranya Ramadoss, General and Family Physician